The present invention relates to a process for determining tumor-associated glycolinkage (hereunder referred to as TAG) in the body fluid of mammals, more particularly, TAG including glycoproteins, glycopeptides, glycolipids and/or sugars having a certain specific terminus which increases with the proliferation of undifferentiated cells, particularly tumorous or cancerous cells.
Methods are known for diagnosing cancer by measuring a specific glycoprotein which is specifically produced in patients with cancer. Most of these methods utilize the antigenicity of protein moiety of the glycoprotein; for example, a method for diagnosing primary liver cancer by measuring .alpha..sub.1 -fetoprotein and a method for diagnosing cancer of a digestive organ, particularly rectal cancer, by measuring CEA are known (Igaku no Ayumi (Progress in Medicine), 106, 5, Fifth Saturday Special Issue, pp. 235-250 (1978)). But these diagnostic methods are coparatively limited in their applicability.
Further investigations have revealed that the body fluid of a patient with cancer contains TAG produced by undifferentiated cells (mostly cancerous cells) and released into the body fluid, and that such TAG differs considerably from the sugars produced by differentiated cells (mostly normal cells) and released into the body fluid with respect to the sugar chain structure, sugar chain length and kind of constituent sugar residue. It has also been found to determine the level of TAG in a sample of body fluid which comprises reacting the TAG in a sample of body fluid with a lectin which can specifically bind with galactose-(.beta.1.fwdarw.3 or .sym.1.fwdarw.4)-N-acetylglucosamine and/or galactose-(.beta.1.fwdarw.3 or .beta.1.fwdarw.4)-N-acetylgalactosamine terminus (GB-2043890A, U.S. patent application Ser. No. 187,890, filed on Sept. 17, 1980).
In view of increasing desire for obtaining methods of measuring the level of TAG and diagnostic methods which are less limited in their applicability and have improved sensitivity extensive investigations have been made, and as a result found that TAG contains glycoproteins, glycopeptides, glycolipids and/or sugars having N-acetyl-D-galactosamine (hereunder referred to as AG) or L-fucose terminus, that it is specifically bound with certain kinds of lectins (hereunder a lectin which can be bound specifically with AG terminus is referred to as AG-binding lectin and that which can be bound specifically with L-fucose terminus is referred to as L-fucose-binding lectin), and that therefore, by reacting the TAG in the body fluid with an AG-binding lectin or L-fucose-binding lectin (hereunder both the lectins sometimes are referred to as specific lectin), cancer cells can be detected, the degree of their proliferation can be checked and their growth profile can be known for cancer diagnosis. The present invention has been accomplished on the basis of this finding.